The invention relates to a feed device for a shaft furnace, in particular a blast furnacer, according to the precharacterizing clause of Claim 1.
Many different devices are known for the purpose of feeding materials into (i.e., charging) a shaft furnace. So that the materials fed in are uniformly distributed over the cross-sectional area of the shaft, decades ago it was proposed to use rotatable charging platforms with a likewise rotatable distributor disposed eccentrically with respect to the axis of the furnace. With such a feed device, which causes the opening of the distributor to be guidedover the furnace cross section along two superimposed arcs, the material can be fed into the furnace quite uniformly, without the formation of obvious conical heaps.
A somewhat different arrangement, such as is known from the German patent DE 295 15 419 U1, comprises a revolving chute with a cylindrical housing that can be driven so as to rotate, multiple feed chutes attached to the outlet of the housing, which have different radial extents, and a distributor chute disposed in the housing, the end of which opens into a feed chute and can be rotated with the housing, such that the distributor chute can be displaced within the housing and variably positioned with respect to the feed chutes, as desired. With this arrangement the profile of the loaded substance can be made to conform to a specific shape, but the apparatus is relatively complicated and costly to construct.
The patent DE-PS 868913 discloses variously shaped charging devices for blast furnaces, the central element of which is a first funnel with a proboscis-shaped outlet, through which passes the material that is to be brought to the edge of the furnace, and a second funnel with vertical outlet, which guides the material to the middle of the furnace. This arrangement, again, is characterized by an expensive and bulky construction, and furthermore it is only to a very limited extent that it allows different materials to be loaded so as to form a particular, desired profile.
Another rotatable feed device, known from DE-AS 1 169 474, comprises a plurality of distributor chutes distributed around the circumference of a circle, and in addition a nearly central and a peripheral distributor chute, all of which are filled by a suitably guided funnel chute. In this arrangement the position of the opening at an arbitrary point on the shaft cross section cannot be freely adjusted, and this device again is complicated and costly to construct.
From DE 28 25 718 C2 and other patents of the same proprietor a feed device for a shaft furnace is known, the central feature of which is a distributor chute with a universal-joint suspension, which can be positioned at various angles with respect to the axis of the furnace, by using a suitable mechanism to rotate it about two axes that are perpendicular to one another. This device makes it possible for materials to be fed into the shaft at well defined positions over its cross section, but its drive mechanism is structurally elaborate and space-consuming.
It is thus the objective of the present invention to disclose an improved feed device of this generic kind which can be implemented in a particularly space- and material-saving manner.
This objective is achieved by a feed device with the characteristics given in Claim 1.
The invention includes the fundamental thought that a feed chute, oriented at an angle to the furnace wall, is fixedly attached to a central, rotatable base body. The chute is in turn divided into an upper and a lower part, the lower part being rotatable with respect to the upper part. Because in this solution only one feed chute (with relatively short overall length) is provided, it can be constructed from a particularly small amount of material. Furthermore, its pivoting mechanism is not under a heavy mechanical load, and hence need not be correspondingly stable in construction, nor does it require an extra, rotatable distributor device; therefore it is relatively easy to construct and takes up relatively little space.
In a preferred embodiment the upper and lower parts are substantially cylindrical in shape (tubular), in particular elliptical or semi elliptical, and when the lower part is in the appropriate angular position with respect to the upper part, the whole arrangement forms a two-piece tube attached at an angle to the outlet of the base body. This embodiment ensures that the pseudo-fluid substance to be fed into the furnace will run out unobstructed and with little friction.
The geometrical relationships are relatively simple when the axis of rotation of the lower part is parallel to the vertical axis of rotation of the base body, and both axes are perpendicular to the plane that separates the lower from the upper part (in which the movement of the lower part with respect to the upper part is guided).
The drive mechanism for the housing (and upper part) is advantageously implemented in a manner known per se, by an electric motor with a combination of pinion and toothed wheel rim, such that the pinion of the drive motor is engaged by a rim gear that is fixed to the base body in a rotationally stable manner. The drive mechanism for the lower part also, in an advantageous embodiment, comprises a combination of pinion and toothed wheel rim, and in this case the toothed rim in particular encloses the outlet of the base body. In a first advantageous embodiment there is attached to this latter toothed wheel a connecting-rod arrangement that is connected by he way of joints at one end to the wheel and by way of joints at the other end to the lower part of the feed chute.
In an alternative embodiment, the drive mechanism for the lower part of the feed chute comprises an output shaft, at the end of which that adjoins the lower part there is disposed a pinion that interacts with another toothed wheel rim that encloses the lower part in a rotationally stable manner.
Both the upper part and the lower part advantageously rotate over a range of angles amounting substantially to 360xc2x0.
With regard to enabling the loading profile to be predetermined in detail, the proposed solution is particularly advantageous in the embodiment with at least two reservoirs for a first and a second material to be fed in, which open into the base body of the feed device and either of which can be emptied into the base body as desired. Because the degree of opening of the retaining flap of the reservoir is determined by the current angles of rotation of the upper and lower part of the feed chute relative to one another, one or the other of the materials (or, where appropriate, other materials to be fed in) can be loaded in predetermined amounts at preselected places on the cross section of the shaft.
Such a differentiated feeding can be accomplished in an especially advantageous manner with an embodiment incorporating a feed-control unit that on the input side comprises means for determining the angular positions of the upper and lower parts (and hence the momentary feed point), whereas on the output side flap actuators for the outlet flaps of the reservoirs are disposed.
In a feed device in the broader sense, between the reservoir or reservoirs a valve arrangement is provided, which in a preferred embodiment comprises a flow-control valve and a gas-tight shut-off valve for each reservoir. This valve arrangement is advantageously designed as a compact valve assembly, which preferably can be displaced as a whole, together with the associated valve drive means, both with respect to the shaft furnace and with respect to the reservoir or reservoirs.
An inlet flange of the shaft furnace is preferably sealed with respect to a flange of the above-mentioned valve assembly that is in contact therewith, which can be achieved particularly reliably and permanently by using a compensator with a press-on device that compensates for thermal expansion. Such a device comprises a hydraulic press-on device orxe2x80x94as has been disclosed for example in the applicant""s patent EP 0 609 406 B1xe2x80x94thermodynamic press-on devices.
Furthermore, a feed funnel is advantageously disposed between the reservoir or each reservoir and the valve assembly. At its outlet the flow-control valve associated with the above-mentioned valve arrangement is disposed, whereas at the outlet from each reservoir into the associated funnel an additional, gas-tight shut-off valve is disposed, which enables the substance to be filled into the funnel without making contact with the sealing surfaces of the valve.